The traditional monopolies of electrical utility companies have been relaxed in the past few years in the European Union, in the United States and in other countries. There has developed as a result a growing wholesale electricity supply market for electrical power. Utility companies, independent power producers, and power marketers as well as brokers are some of the participants in the volatile electricity supply market. It is known, for example, that variables such as the time of day and date, weather, temperature and oil prices play a role in the pricing of electricity in a given region. Similarly, the way in which the electrical power transmission line (or power grid) and the pricing of electricity play a role for in the storage of fuel, such as oil, and other commodities.
Furthermore, the pricing of the electricity is dependent on the operational status of electricity supply generators and use of facilities as well as the transmission capacity of an electric power transmission network (also called power grid). The participants in the electricity supply markets require access to substantially real-time information as well as historical data on the operational status of the electricity supply generation and use facilities as well as the electric power transmission lines in the region. This information allows the development of trading strategies in electric power and responses to power system events (such as disruptions in the power grid due to failures of transformers).
The relaxation of the monopoly status of traditional electric utility companies has resulted in increased competition for customers among suppliers of electric power. Information relating to the use of electric power by the potential customers would be useful to those involved in the bidding for electrical supply contracts. It would also be advantageous to determine information on the supply and the demand of the electric power over time without having to directly connect to the electrical power transmission lines.
There is also a requirement to monitor the power grid in order to ensure an increasing stability of the power grid.
One of the issues related to the relaxation of the monopoly status of traditional electric utilities is the requirement to determine power system disturbances in the power grid. U.S. Pat. No. 7,519,454 (Gardner et al., assigned to Virginia Tech Intellectual Properties) teaches a system for detecting and locating the disturbance events within the power group which includes a series of frequency disturbance recorders taking measures in the power group at disparate points of the power group and an information management system which is configured to receive data from the series of the recorders and to analyze the received data. The frequency data recorders include a low pass filter to eliminate high frequency components in a measured 110V AC signal from a wall socket. The system of US '454 further includes a communications network interconnecting the series of frequency data recorders and the information management system. The information management system is configured to examine orders and patterns of receipt of the frequency changes caused by the disturbance event and to triangulate a location of the disturbance event based on the orders and patterns of receipt of the frequency changes. The teachings of the US '454 patent require the measurement of a complete cycle of the frequency to determine a change in the frequency and also lose information by eliminating the high frequencies in the 110V AC signal.
Methods and systems for the measurement for the electric power transmission are known from several prior art documents. For example U.S. Pat. No. 6,714,000 (Staats, assigned to Genscape, Inc.) teaches a method for the remote monitoring of the magnitude and the direction of net electrical power and current flow to or from a facility monitored over a prolonged period of time. The method described in the Staats US '000 Patent includes the detection and the measurement of the magnetic field emanating from the monitored electrical power transmission lines and detecting a signal that is synchronized to the power system frequency emanating from the power lines. The method further includes valuation, storing and transmission of the data on the electromagnetic field that emanates from the electrical power transmission line.
A further International Patent Application No. WO2006/112839 (Genscape Intangible Holding, Inc.) also teaches a method and a system for the substantially real-time monitoring of the operational dynamics of power plants and other components in an AC power grid. The monitoring is done by using information collected from a network of power grid frequency detection and reporting devices. The invention allows for the real-time detection and reporting of certain power grid events, such as a power plant trips or failures.
International Patent Application No. WO2007/030121 (Genscape Intangible Holding, Inc.) teaches a system for monitoring the power flow along an electric power transmission line that includes a plurality of magnetic field monitors placed at selected positions. The magnetic field monitors have two magnetometers with their sensitive axis placed either in the horizontal or vertical direction. A detailed description of such magnetic field monitors is found in U.S. Pat. No. 6,771,058 (Lapinski). The system further includes a central processing facility for the communication of the power flow to an end user.
European Patent No. EP 1 297 347 (Genscape Intangible Holding, Inc.) discloses an apparatus for remotely measuring and monitoring an electric power transmission line. The apparatus comprises a first sensor which is responsive to a first component of a magnetic flux density associated with the electric power transmission lines and which outputs a volt proportional to the magnetic flex density generated by current flowing through set electrical power transmission line. The apparatus further includes a second sensor which outputs a voltage proportional to a net electrical potential associated with the electrical power transmission line. The values for the voltage and the current flowing through the electrical power transmission line are passed to a central processing facility which combines the phase of the measured electrical potential with the phase of the measured magnetic flex density in order to determine the phase of the electrical potential relative to the magnetic flux density and that by determining from the face of the electrical potential relative to the magnetic flux density. The phase angle of the current flowing through the electrical power transmission line with respect to the voltage of the transmission line is also determined A power factor on the electric power transmission line and the magnitude and the direction of the power flowing through the electrical power transmission line is thereby calculated. It should be noted that the voltage sensor and the magnetic flux sensor are substantially co-located, as can be seen from FIG. 1 of the patent.
Other companies also measure power flowing along electric power transmission lines. For example, the Norwegian company powermonitor.org supplies information about the German power plants. Their product is described in the article “Slik drives strøm-spionasje”, Økonomisk Rapport April 2006, 40-41. Another Norwegian company, Energieinfo AS, Stavern, has filed a Norwegian patent application entitled “Fremgangsmåte og apparat for overvåkning av produksjon og overføring av elektrisk kraft” (Application No. NO 2007 2653).